1. Field of Invention
The present invention relates to a liquid crystal display, and more particularly to a transflective liquid crystal display capable of reducing an aperture loss of a transmission region by forming a reflection region at a center of a pixel region.
2. Description of the Prior Art
A liquid crystal display (LCD) comprises a thin film transistor (TFT) substrate having pixel electrodes formed thereon, a color filter substrate having a common electrode formed thereon, and a liquid crystal layer interposed between the two substrates. The LCD displays an image by controlling the alignment of liquid crystal molecules, which is done by applying voltages to the pixel electrode and the common electrode. The amount of light transmitted through a liquid crystal layer is adjusted by the alignment of the LC molecules.
Since an LCD is not self-luminescent, light is supplied from the outside to form an image. LCDs are classified into transmissive, reflective and transflective types according to the type of light source. The transmissive LCD displays an image using a backlight positioned in the rear of an LCD panel, and the reflective LCD displays an image using ambient light. The transflective LCD, which is a combination of the transmissive and reflective LCDs, operates in a transmission mode when an image is displayed using a backlight unit incorporated into the LCD device when the amount of ambient light is insufficient to display the image of the desired quality and luminescence. The transflective LCD, however, operates in a reflection mode when there is enough ambient light. The transflective LCD is used for medium- and small LCDs. In the transflective LCD, a portion of a pixel region defines a transmission region, and the other portion of the pixel region defines a reflective region.
A vertical alignment mode LCD, in which the major axes of liquid crystal molecules are aligned vertically with respect to the TFT and color filter substrates in the absence of an electric field, has been receiving much attention because of its ability to achieve high contrast ratio and a wide viewing angle. In order to realize the wide viewing angle in the vertical alignment mode LCD, there is a method of forming a cut-away pattern or a projection on an electrode. According to such a method, a fringe field is formed and the directions in which liquid crystals are inclined are uniformly distributed, thereby securing a wide viewing angle. Particularly, a PVA (Patterned Vertical Alignment) mode, in which a cut-away pattern is formed on an electrode, has been recognized as a wide viewing angle technology with which an IPS (In Plane Switching) mode can be replaced.
In a transflective PVA LCD, in which the transflective and PVA modes are combined, and which is employed in medium and small products such as mobile phones, a transmission region is formed in a portion of a pixel region defined at an intersection region of gate and data lines, a reflection region is formed in the other portion of the pixel region, and a cut-away pattern is formed in the transmission region. In the transflective PVA LCD used for such medium and small products, the reflection region is formed in a gate line side of the pixel region with a TFT formed thereon, and the other portion of the pixel region is formed as the transmission region. However, if the transmission region is larger than the reflection region, the transmission region cannot be formed with a single domain due to the characteristics of the medium and small transflective PVA LCD. So, the transmission region is divided into two regions. In order to operate the LCD in a PVA mode by dividing the transmission region into two regions, the divided domains are spaced apart from each other. This configuration can be problematic in that it reduces the aperture ratio by the distance between the divided domains. Further, the two domains are bridged, and the liquid crystals in the bridge region are irregularly aligned so that no image is displayed in the bridge region. This reduction in the aperture ratio in the bridge region is undesirable.